In general, a liquid crystal display device includes a liquid crystal layer sealed between a pair of substrates. One of the paired substrates is a TFT substrate including a plurality of gate lines, a plurality of source lines, a plurality of pixel electrodes, a plurality of TFTs, etc. The other substrate is a counter substrate including a common electrode corresponding to the plurality of pixel electrodes. The liquid crystal layer is sealed with a frame-shaped sealing member surrounding the liquid crystal layer between the TFT substrate and the counter substrate.
Each of the TFT substrate and the counter substrate includes an alignment film formed on a surface facing the liquid crystal layer to control orientation of liquid crystal molecules in the liquid crystal layer. The alignment film is made of a resin film, such as a polyimide film, and rubbing or photo-alignment has been performed on a surface thereof.
The alignment film is formed by applying liquid polyimide on the surfaces of the TFT substrate and the counter substrate, and baking the liquid polyimide to cure. The polyimide may be applied by flexography, ink jet printing, etc.
In forming the alignment film by the ink jet printing, viscosity of an alignment film material such as polyimide needs to be relatively low so that drops of the alignment film material discharged toward the substrate and hit on the substrate can sufficiently spread on the surface of the substrate. However, the low viscosity alignment film material can smoothly spread on the surface of the substrate, and the alignment film material may unnecessarily spread to a region for forming the sealing member.
Patent Documents 1 and 2 propose a technique of preventing the excessive spread of the alignment film material by forming a groove in the TFT substrate between the region for forming the sealing member and a pixel region which contributes to display so that the groove can hold the alignment film material.